Because as we all know, real scientists would never operate from - or be influenced by - philosophical or ideological agendas, or by trivial banalities such as overt threats of tenure removal/career suicide.
/sarcasm>
(sarcasm still off) It's precisely because scientists are human (I'll give some of my old profs the benefit of a doubt here) given to all the influences you mentioned that we rely on data, peer review, reproducibility, constantly questioning old analyses, etc.